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mediaobject — A displayed media object (video, audio, image, etc.)
mediaobject ::= (objectinfo?, (videoobject|audioobject|imageobject|imageobjectco|textobject)+,caption?)
               This element contains a set of alternative
               “media objects.” In DocBook V3.1, three types of
               external objects are defined: VideoObjects,
               AudioObjects, and ImageObjects. Additional
               textual descriptions may be provided with TextObjects.
               
            
Formatted as a displayed block.
                  The primary purpose of the MediaObject is to provide
                  a wrapper around a set of alternative presentations of the same
                  information.
                  
               
                  If possible, the processing system should use the content of the
                  first object within the MediaObject.  If the first
                  object cannot be used, the remaining objects should be
                  considered in the order that they occur.  A processor should use
                  the first object that it can, although it is free to choose any
                  of the remaining objects if the primary one cannot be used.
                  
               
                  Under no circumstances should more than one object in a
                  MediaObject be used or presented at the same time.
                  
               
                  For example, a MediaObject might contain a video, a high
                  resolution image, a low resolution image, a long text description, and
                  a short text description.  In a “high end” online system,
                  the video is used.  For print publishing, the high resolution image is used.
                  For other online systems, either the high or low resolution image is used,
                  possibly including the short text description as the online alternative.
                  In a text-only environment, either the long or short text descriptions are
                  used.
                  
               
These elements contain mediaobject:
                  answer, appendix, appendixinfo, article, articleinfo, bibliodiv, bibliography, bibliographyinfo, blockinfo, blockquote, bookinfo, callout, caution, chapter, chapterinfo, constraintdef, entry, equation, example, figure, footnote, glossary, glossaryinfo, glossdef, glossdiv, important, index, indexdiv, indexinfo, informalequation, informalexample, informalfigure, informaltable, itemizedlist, listitem, msgexplan, msgtext, note, objectinfo, orderedlist, para, partinfo, partintro, preface, prefaceinfo, procedure, qandadiv, qandaset, question, refentryinfo, referenceinfo, refsect1, refsect1info, refsect2, refsect2info, refsect3, refsect3info, refsection, refsectioninfo, refsynopsisdiv, refsynopsisdivinfo, revdescription, screenshot, sect1, sect1info, sect2, sect2info, sect3, sect3info, sect4, sect4info, sect5, sect5info, section, sectioninfo, setindex, setindexinfo, setinfo, sidebar, sidebarinfo, simplesect, step, synopsis, table, taskprerequisites, taskrelated, tasksummary, td, th, tip, variablelist, warning.
               
The following elements occur in mediaobject:
                  audioobject, caption, imageobject, imageobjectco, objectinfo, textobject, videoobject.
               
alt, audioobject, caption, graphic, imageobject, inlinegraphic, inlinemediaobject, textobject, videoobject.